Antimicrobial Efficacy of Aqueous Extracts of Abrus precatorius and Achyranthes aspera Against Streptococcus mutans and Candida albicans: An In Vitro Study.

Background Dental caries and oral candidiasis are among the most common oral diseases and are primarily associated with Streptococcus mutans and Candida albicans. Growing concerns regarding antimicrobial resistance and the adverse effects of synthetic antimicrobial agents have increased interest in plant-derived alternatives. This study evaluated and compared the antimicrobial efficacies of aqueous extracts of Abrus precatorius and Achyranthes aspera against Streptococcus mutans and Candida albicans. Methodology An in vitro experimental study was conducted using aqueous extracts from the leaves of Abrus precatorius and Achyranthes aspera. The antimicrobial activity against Streptococcus mutans (ATCC 25175) and Candida albicans (ATCC 10231) was assessed using the agar well diffusion method. Chlorhexidine and nystatin served as positive controls for antibacterial and antifungal testing, respectively, and distilled water served as the negative control. Minimum inhibitory concentrations (MICs) were determined using the broth microdilution method. Data were analyzed using one-way analysis of variance followed by Tukey's post-hoc test and independent-samples t-test. Results Significant differences in antimicrobial activity were observed among the groups (p < 0.001). Against Streptococcus mutans, Abrus precatorius demonstrated a larger mean zone of inhibition (18.42 ± 1.58 mm) than Achyranthes aspera (15.16 ± 1.47 mm), although chlorhexidine exhibited the greatest antibacterial activity (24.31 ± 1.32 mm). Similarly, against Candida albicans, Abrus precatorius produced a larger inhibition zone (16.87 ± 1.36 mm) than Achyranthes aspera (13.92 ± 1.41 mm), whereas nystatin showed the highest antifungal activity (22.74 ± 1.24 mm). Abrus precatorius also demonstrated significantly lower MIC values against both microorganisms, indicating a greater antimicrobial potency. Conclusions Both aqueous plant extracts exhibited significant antibacterial and antifungal activity. Abrus precatorius showed superior antimicrobial efficacy compared to Achyranthes aspera; however, both extracts were less effective than the standard antimicrobial agents. These findings suggest the potential application of these herbal extracts in the development of oral healthcare products.